The invention relates to a dispensing system, and more particularly to a cup dispenser for supporting a stack of cups and releasing cups one at a time from the bottom of the stack.
Such dispensers generally are intended to provide support for the cups such that the bottom cup may be pulled downwardly and removed from the dispenser while the other cups remain supported therein. When a user grasps the bottom cup and pulls it downward, the bottom cup may deform so as to engage the side wall of the second cup from the bottom. This may result in substantial downward force on the second cup as the bottom cup is withdrawn. Additional downward force on the second cup may result from a partial vacuum between the bottom cup and the second cup if the bottom cup is pulled downward rapidly. The weight of the stack of cups may also place downward force on the second cup. These forces may prevent the bottom cup from separating from the stack freely, and may cause more than one cup to be dispensed when only a single cup is desired.
The downward force due to friction between the cups is partially dependent upon the magnitude of gripping force applied to the bottom cup, which is in turn partially dependent on the resistance to withdrawal of the bottom cup provided by the dispensing system. If the resistance to withdrawal is too great, a user will be likely to grip the bottom cup tightly when attempting to remove it, thus generating relatively high frictional forces between the side walls of the lower cups in the stack, and possibly withdrawing more than one cup. However, if the resistance to withdrawal is too low, then withdrawal of multiple cups can result from even relatively low gripping forces.
The downward force due to friction between the cups is also partially dependent on the interaction of the cups with the interior of the dispenser. The bottom cup may be deformed by the interior of the dispenser as it is drawn downwardly so that portions of the bottom cup are deflected inwardly to contact the second cup. The resultant frictional force will depend not only on the material of the cups and the inward force on the bottom cup, but also on the ability of the second cup to deform in response to the force exerted thereon by the bottom cup. The ability of the second cup to deform is a function of its own stiffness and of the stiffness of other cups contained therein. When the dispenser is nearly empty, containing, for example, only two or three cups, the second cup can deform much more readily than when the dispenser is full.
In the past, dispensers for plastic cups have generally employed resilient members such as brushes which engage the bottom cup to support the stack prior to withdrawal of the bottom cup, and which are sufficiently flexible that they can bend as the bottom cup is withdrawn, then spring back after the rim of the bottom cup has passed to engage the rim of the second cup. Such resilient members add to the cost of the dispenser, and may wear out.
Some prior art dispensers for use with paper cups have employed relatively rigid, inwardly extending flutes to deflect the cup rim inwardly at three or four points as the cup is withdrawn, but such dispensers have not been suitable for use with plastic cups, due largely to the greater stiffness of plastic cups.
It is a general object of the invention to provide an improved dispenser for one-by-one dispensing of plastic cups.
It is an additional object of the invention to provide a cup dispensing system employing a one-piece, molded housing for holding a stack of cups and controlling dispensing thereof.
Further objects and advantages of the invention are set forth below.